SU753835A1 - Method of protecting construction articles - Google Patents

Abstract

1487225 Treating alkaline constructional materials CHEMIEWERK NUNCHRITZ VEB 11 Nov 1974 [13 Nov 1973] 48617/74 Heading ClH [Also in Division D1] Constructional parts made from alkaline constructional materials have their water repellancy and corrosion resistance increased by treatment with gases or vapours of at least one organo-fluoro silane of the general formula R n SiF 4-n in which R is an organic radical, preferably methyl or ethyl and n is 1, 2 or 3. The constructional material may be Portland cement, lime cement, blast furnace cement, sulphate resistant cement or a special cement, e.g. asbestos cement or silica concrete, concrete with a cement, lime-sand or magnesia binder, or a gas or foamed concrete. The organo-fluoro silane may be a mixture of methyl trifluorosilane and dimethyl difluoro silane, and may be admixed with silicon tetrafluoride and/or an inert gas. Treatment may be at ambient or elevated temperature and at, above or below atmospheric pressure. Wet or moist as well as dry materials may be treated.

Description

The invention relates to methods (Protection of building products and imparting resistance to corrosion against them, mainly under the action of acids and salt solutions. A known method of protection against corrosion of concrete tanks, by treating with gaseous silicon tetrafluoride fl. The known method makes it possible to improve the protective anti-corrosion properties of concrete, but it does not achieve its water-repellent ability. The closest to the described invention to the technical essence and the achieved result is the method of protection page products including the treatment of the product with vaporous organosilanes, for example, methylchlorosilane for 40-v50 min at 2. The known method does not allow to increase the corrosion resistance of building products, because the impact of vapor-like sword orhlgl; C4. - Body products lead to the formation of hygroscopic calcium chloride, which causes destruction of the structure of the building product and, in addition, water-repellent properties. The purpose of the invention is to increase the corrosion resistance and durability of the product, regardless of its moisture content and degree of cure. This is achieved by the fact that in the method of protection of building products, including the treatment of the product with vaporous organoslans, the product is treated with organofluorosilanes of the general formula Rn ST P4-p organic radical from the group of ethyl, methyl, alkenyl, aromatic, and And takes values from 1 up to 3. The treatment is also carried out with a mixture of methyl fluorosilanes, which are formed during the fluorination of residues from the distillation of the products of the synthesis of methyl chlorosilanes. In this case, the treatment is carried out under normal conditions. 37 The described method is carried out as follows. . The finished building component, made on the basis of a mineral alkaline reaction, is treated with gaseous or vaporous organofluorosilane of the general formula Rn 5i 4-c where R is an organic residue, mainly methyl or ethyl radical, and p takes on the values of NIN numbers from 1 to 3, mostly 1.

Moreover, in some cases, the treatment is carried out in the presence of silicon tetrafluoride and / or an inert gas. Through the pores, the gas penetrates into the building detail and reacts with an exothermic effect with alkaline components to form fluorides metallots, predominantly calcium fluoride, which, in contrast to the corresponding initial oxides, hydroxides and carbonate salts, is completely resistant to water or aqueous acid solutions. or salt. At the same time, organopolysiloxane is formed, which, due to its hydrophobic action, prevents water penetration. In this case, the hydrophobization occurs in a much greater thickness of the layer than can be achieved by dyeing or spraying using a silicone solution. In contrast to treating the surface of cement with tetrafluoride silicon, in which the liberated water in a free state is absorbed by precipitating silicic acid, the reaction of organofluorosilane with metal hydroxides leads to the repulsion and excretion of water.

At the same time, the structure in the reaction layer is compacted in such a way that an improvement in mechanical is achieved. properties of concrete — its strength increases, which exceeds the strength of concrete treated with silicon tetrafluoride, with the degree of hydrophobization averaging 85%.

Methyl fluorosilane can be used as an organofluorosilane. It can be used in pure form or in conjunction with dimethyldifluorosilane and / or trimethyl fluorosilane. The latter mixture is formed by treating with a fluorinating agent residues resulting from the distillation of the products of the synthesis of methyl chlorosilane. Other low boiling organofluorosilanes are also suitable: ethyl fluorosilane, vinyl fluorosilane, propyl

pressures x When processing very dense concrete under normal conditions without applying pressure, a compaction of resins between 1 and 4 mm thick can be achieved. It does not have (the part is decisive in the wet, wet, air-dry or dried state.

By varying the gas pressure, the treatment time, the concentration of the reaction gas, the thickness of the protective layer and, therefore, the degree of protective effect can be varied within specified limits.

The method is carried out in a chamber lined with acid-resistant material or in a plastic synthetic mass scraper, in an aktoklav or on a camera tape.

continuous operation.

Since the density of gaseous organofluorosilane is greater than the density of air, the inner walls of hollow tanks made of concrete or other alkaline building materials, such as silos, tanks, chimneys, etc., are processed by introducing the reaction gas into a hollow tank, while air is displaced, and the container is closed, for example, with a film of a polymeric material.

Example 1. From Portland cement (PZ400), resistant to Portland cement sulphates 5 (SPZ 300) and slag Portland cement (HOZ 225), when using test sand with grain fraction O, O8 ... 1 mm (ratio S | Z 3 N M | 2 Oh, 5), we made a prize with measurements of 10 x 10 x 60 mm. The manufactured prisms were kept for 14–21 days under water, then dried in air to constant weight, and immediately thereafter kept in a desiccator at room temperature and atmospheric pressure for 48 hours in the atmosphere of methyl trifluorosilane. 35 fluorosilane or pairs of higher boiling organofluorosilanes, for example butyl fluorosilanes, or phenylfluorosilanes. Gases or vapors may be applied in pure form or may be diluted with an inert gas. The method can be carried out at room temperature or at elevated temperature. The treatment can be carried out both at atmospheric pressure and at lower or higher levels. Prisms made in this way were treated with a mixture of tetrafate silicon and methyl trifluoro silane (3: 4) or silicon tetrafluoride, methyl trifluoro silane and dimethyl difluoro silane (3: 3.6: 0.4) . Table 1 contrasts the limits of compressive strength of these prisms with the strengths of uneducated prisms and prisms, treated equally with gaseous pure tetrafluoride silicon. It can be concluded that the untreated prisms have the lowest strength, compared with the highest strength of prisms treated with a gas containing methyl trifluorosilane. The increase in strength reaches 100 percent. The treatment of prisms with the above gas or vapor, respectively, of mixtures under reduced pressure or under increased pressure leads equally to good results. The compressive strength of small-sized prisms processed from various solutions is presented in Table. one

Table

SiF

J

Water absorption and degree of water repellency of samples sustained to constant weight in water are given in Table 3. From the tabular data it follows that the water absorption of prisms treated with methyltrifluorotrans is approximately 85 percent less, the water absorption of prisms treated by tetrafluorosilane is only 20-25% less than Water absorption of raw prisms. Tabl. 1 | Strengths at Processing. Compression, kg / cm iJpz pTz HOZ ,, 599 533 503 5iVCH ,, SiF - "- fCH ,, Specific gas permeability of P Z -prism and HOZ-prism is compared in Table 2, From the table it can be seen that Treatment with both methyltrifluorosilane and tetrafluorosilane leads to an increase in gas permeability and, consequently, to less clogging of the pores. The specific gas permeability of the cement forms prepared in various ways is presented in Table. 2. Table2

From the table it can be concluded that: gas treatment of samples both in the wet and in the wet state occurs with success.

Example 4. Prisms with PZ -; in zuyu were made in accordance with example 1, made a gas treatment and placed in a corrosive solution. The corrosion course was determined by increasing the mass of the prism after 28 days, Table 6.

An increase in the mass of prisms after 28 days of storage in a corrosive solution is presented in Table 6.

Table

A significantly smaller change in the mass of samples treated with methyltrifluoro- silane confirms the inhibitory corrosion effect of methyltrifluoro- silane.

Example 5. Concrete prisms measuring 4 x 4 x 16 cm from PZ and gravel as usual were set and after month of manufacture, sprinkled with methyl trifluorosilane at room temperature. Weight gain

Processing. Increasing mass in% after storage. Example 6. The concrete prisms used in Example 5 were saturated in a tube equipped with a heating jacket with methyl trifluorosilane at the temperature indicated in Table 8. After 28 days of storage, water absorption was determined (for comparison values see in table 7). Equally, in Table 8, the recoil values of water (the mass of water given off during the subsequent, the essence of sustained prisms in air) shows that the samples treated with gas at or above temperature absorb part of the water irreversibly. Water absorption and return of water with concrete prisms treated with gaseous

prisms when stored in a corrosive solution (table 7) shows that exposed for long periods of exposure to atmospheric air parts made of concrete, i.e., fully carbonized, can also be subjected to corrosion protection, as well as freshly made parts.

An increase in the mass of prisms from concrete after 28 days of storage in a corrosive solution is presented in Table. 7,

T table 7

in solution, rifluorosilane with elevated atura is presented in Table. 8. Table 8. 7 The penetration depth of fluorosilane, determined by cutting the sample and treating the cut surface of phenolphthalein solutions, was in the case of PZ from 1 to 2 mm, in the case of 5PZ from 1 to 3 mm and in the case of HOZ from 2 to 4 mm. Example 2. Small prisms from 5PI were prepared by analogy with that described in Example 1, were treated with a reaction gas with a gas and 28 days after their manufacture, were stirred into the following solutions: 1.HC C - pH 1 (approximately 0.1 mol 2.39 g of magnesium sulphate / liter of water 3.386 g of magnesium sulphate / l of water Example 3. Small prisms of cPZ-, 5PZ- and HOZ - binder were made according to example 1 and in various cases in wet, wet and dry conditions were treated with gaseous methyltrifluorosilane 28 days after their manufacture, the prize was placed in a solution (Example 2) and, ie 180 days is determined about NOSTA limit under compression.

Table4 5 4.305 g of magnesium chloride / l of water. 5. Piped water. Samples that, in the case of reaction gas treatment, had no surface corrosion damage, were evaluated by measuring the compressive strength after storage for 180 days. 1 The results obtained, together with the values obtained for samples untreated with gas and treated with tetrafluoride silicon, are presented in Table 4. They confirm the presence of a corrosion retarding effect in the case of treatment with Methyl trifluorosilane. The compressive strength of the PTFISM, after being deposited in a corrosive solution, is presented in Table. 4 The obtained results are counteracted in table 5 values obtained for untreated samples and treated with tetrafgorsilan by the indicated method. The compressive strength of prisms treated with a gas in a different moisture state after 180 days of retention in a solution of magnesium chloride (305 g of salt per liter of water) is presented in Table. 5. Table 5 Example 7. Concrete prisms used in npimer 5 were treated at room temperature to saturation with a mixture of methyl trifluorosilanes, which were obtained as a result of the interaction of tatts formed during the distillation of the products of the direct synthesis of methyl chlorosilanes with aqueous hydrofluoric acid (V), and contained 92% methyltrifluorosilane, 7% dimethyldifluorosilane and 1% trimethyl fluorosilane. After 10 weeks, the samples aged in the corrosive solution showed after 28 days the following increase in weight (table 9, for comparison, see table 7), an increase in the mass of concrete prisms that were treated with a GaO mixture of methylfluorosilanes and aged for 28 days in a corrosive solution presented in Table. 9 Table9 Mass increase Corrosive solution

Water

10% on HE

0.1 NV NS I

Example 8. Concrete prisms used in Example 5 were treated at room temperature to saturation with gaseous vinyl trifluoro silane. After 4 weeks, the samples aged in the corrosive solution showed, after 28 days, the following weight gain, table 10.

The elevation of the mass of prisms from concrete, which were treated with gaseous vishstrnfluorosilane and kept in a corrosive solution for 28 days, is presented in the table. 1O.

Example 10. Test samples with measurements of 40 x 40 x 16O mm from dense silicate concrete (binder ratio - water 0.62, solid matter ratio (unground sand), binder ratio 5.1) were treated with gas by analogy with that described in Example 1. Measured directly after this water absorption value and the degree of hydrophobicity calculated from them according to Rietmeyer, show a strong hydrophobic effect of methyltrifluoronylan even in the case of silicate concrete, table 11.

The water absorption (WA) and the degree of hydrophobicity (H °) of the samples processed from the platelet silicate concrete are presented in Table. eleven.

T a and blitz 11 Table 10 Corrosive growth Increase in mass, thief 0.1 M HC, Example 9. Pairs of boiling phenyltrifluorosilane (102 C) were passed for 1 hour through a tube that was heated to 110–115 ° C. prism of concrete, used in example 6, Immediately after this heating was continued for 2 hours at the specified temperature. The cooled dried prisms were absorbed at 28 days of storage in water of 0.94% water. The return of water during the subsequent drying in air was 0.43%. Raw prisms absorbed 4.3% of the water. The increase in the specific gas permeability of the dense silicate concrete treated in this way is indicated in Table 12. The specific gas permeability of the samples of dense silicate concrete treated by gas is presented in Table. Table 12 Specific gas production (pico-Pr The gas penetration depth, which can be determined by treating the cut surface with an alizarin solution, was 2.5 mm for treating gaseous tetrafluoro-silicon, and 3.5 mm silane for silane and a mixture of tetrafluorosilane and methyltrifluoro silane with 3.0 mm. Certain limits of tensile strength during bending and compressive strength are presented in Table 13. The tensile strength during bending and compression strengths of processed samples of dense silicate Concrete represented vtabl. 13 TABLE 13

Table 14. Example 11. Prototypes with measurements of 40 x 40 x 160 mm from gas-silicate concrete (kansusha with a density of 0.86 g / cm) were treated with gaseous tetrafluorinated gas and methane fluoro-silane by analogy with that described in Example 1. They were determined immediately In this case, water absorption and the Riethmeuer degree of gibbrobiization that were computed from them clearly show the hydrophobic effect of methyltrifluorosilane, table 14. The absorption of air (WA) and the degree of density of samples of gas-silicate beta processed in different ways presented in Table. 14. Example 12. Prisms of gas silicate concrete with an apparent density of 0.86 g / cm were treated with gaseous methyl trifluorosilane by analogy with that described in example 1 and immediately after that they were placed in a solution containing zoo g of magnesium chloride in 1 liter of water. After 6 months, the samples did not absorb water and swam unchanged on the surface of the solution. Example 13. Gas silicate concrete prisms with an apparent density of 0.86 g / cm were treated with gas by analogy with that described in example 1. Immediately after this, the samples were hydrophobic by measuring the contact angle of the applied water drop, respectively, of the solution. The results obtained are shown in the table. The measurement of the contact angle of the silicate concrete treated with gas is presented in Table 15.

Contact angle (degree) in rasterWorking

The gas penetration depth was from 1 to 3 mm.

Example 14. Prisms with 7x7x4 cm measurements made of dense silicate concrete were treated in a pressure vessel for 4 hours with pure methyltrifluorosilane, respectively, with a mixture consisting of methyltrifluorosilane and tetrafluorosilane tl: l) and the samples were kept directly at this for 480 hours in water

EZ Table 16 contrasted with the resulting result with the vogue

Example 15. Prototypes with measurements of 7 x 2 x 2.5 cm, made of a magnetically-containing binder and asbestos (Kerenite) were saturated in a desiccator at room temperature and atmosphere: f (with a pressure of methyl trifluorosilane, respectively, frgofx; iliai and i Dnocf) eacTBe, after this vytsgrzhi.vali for 48 hours

Table15 thief

untreated prisms that were equally kept for 48O hours in water, and prisms that were pressure treated with tetrafluorosilane for 6 hours and kept for 240 hours in water.

The penetration depth of methyl trifluorosilane was about 10 mm.

The water absorption (WA) and step of gadrophobnization (H) with fluorosilanes under pressure from the treated prisms of dense silicate concrete are presented in Table. sixteen.

Table 16

In a solution of chloro-magnesium or in a 4O / 0-th solution of sodium hydroxide. The weight gain in each case is shown in table 1 7.

The increase in the mass of the sample: KofrouuTa samples treated with fluorine-silanes after incubation for 18-18 hours in a corrosive solution} 0 is presented in Table 17.

Treatment

CHojS-iF ,, S-i

Formula and inventive and

Claims (3)

1. A method of protecting building products, including treating the product with vaporous organosilanes, characterized in that, in order to increase the corrosion resistance and strength of the product, regardless of its content of VL9GI and the degree of cure, the product is treated with organofluorosilanes of the general formula R n5iF, Rde R; - organic radical of the vi3 group: ethyl, methyl, alkenyl, aromatic, and n takes values from 1 to 3. 2. The method according to claim 1, about t and h and y and the fact that the processing will be performed by the person 17 Weight gain in% after storage in solution ten 6.5 Not specified42, 0 defined 56 87.0 are a mixture of methylfluorosilanes resulting from the fluorination of residues from the distillation of the methyl chloro-α synthesis products. silanes. 3. The method according to paragraphs. 1 and 2, characterized in that the treatment is carried out under normal conditions. Sources of information taken into account in the examination 1. Corrosion protection of reinforced concrete tanks by treatment with SiF, .Kovacs Jcbz-seiqsToeton -tartdj jszerVezeteV vedeeme eiF4gfaz1 ez.eeesseeT Mag-sar epitoipar / i bi, 12., 219-22o. 2. USSR author's certificate No. 340638, cl. C O4 B 41/28, 1E7O.